This invention relates to a coated textile fabric for use in an air-holding vehicle occupant restraint system and, more particularly, to a fabric having a plurality of polymeric layers coated thereon for use in such a vehicle occupant restraint system and the method of coating said textile fabric.
The current restraint systems for vehicles include driver side air bags which are housed in the steering wheel in a collapsed, folded condition adapted to be deployed instantaneously in an inflated condition by injection of a gas upon the occurrence of a collision. The advent of such driver-side air bags has resulted in a significant decrease in automotive fatalities.
Air bag restraint systems have also been located in the dashboard in order to provide a comparable measure of protection to the passenger seated adjacent the driver.
The automotive industry has recently introduced air bags which are housed in the backs of the front seats or the rear seats to protect the cabin occupants in the event of a collision occurring on either side of the vehicle.
A still further safety feature which is being marketed for passenger vehicles, especially sport utility vehicles (SUV), are air-holding curtains designed to provide a cushioning effect in the event of roll-over accidents. These curtains are housed in the roof of the vehicle beneath the headliner and deploy along the interior sidewalls in the event of a rollover.
One means of improving the efficacy of air-holding vehicle restraint systems has addressed the coatings to be applied to the textile substrate to improve air retention.
In the prior art, coated air bags were made by coating a nylon or polyester substrate with chloroprene or silicone rubber. They were not, however, susceptible to heat sealing. In order to ameliorate the problems inherent in chloroprene and silicone rubber coatings, it has been disclosed in the art to coat the fabric substrate with certain aqueous silicone emulsion compositions which yields a tack-free surface and high mechanical strength to prevent cracking upon inflation of the airbag. Such an air bag coating composition is disclosed in Inoue et al., U.S. Pat. No. 5,254,621.
Despite the advances in air bag coating technology, the problems of controlling air permeability, air pressure, and volume still remain when stitching is involved.
It has now been found that if a knit, woven or non-woven textile fabric substrate is first coated with a polyurethane layer and, thereafter, the polyurethane layer is coated with a layer of an elastomeric polysiloxane, the air bag formed therefrom not only has superior air holding permeability and volume, but also possesses superior heat resistance which is of special significance during inflation due to the very high temperatures generated when hot inflation gases are employed. Furthermore, since silicone is inert, it will not block or stick to itself even during extended periods of non-use, while housed in the vehicle, but will nonetheless deploy in an efficient and rapid manner when the need arises to provide the required protection during a crash.